Minimum Thermal Conductivity in Weak Topological Insulators with Bismuth-Based Stack Structure

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• 作者：Ping Wei ; Jiong Yang ; Liang Guo ; Shanyu Wang ; Lihua Wu ; Xianfan Xu ; Wenyu Zhao ; Qingjie Zhang ; Wenqing Zhang ; Mildred S. Dresselhaus and Jihui Yang
• 刊名：Advanced Functional Materials
• 出版年：2016
• 出版时间：August 2, 2016
• 年：2016
• 卷：26
• 期：29
• 页码：5360-5367
• 全文大小：1069K
• ISSN：1616-3028

文摘

Contrary to the conventional belief that the consideration for topological insulators (TIs) as potential thermoelectrics is due to their excellent electrical properties benefiting from the topological surface states, this work shows that the 3D weak TIs, formed by alternating stacks of quantum spin Hall layers and normal insulator (NI) layers, can also be decent thermoelectrics because of their focus on minimum thermal conductivity. The minimum lattice thermal conductivity is experimentally confirmed in Bi₁₄Rh₃I₉ and theoretically predicted for Bi₂TeI at room temperature. It is revealed that the topologically “trivial” NI layers play a surprisingly critical role in hindering phonon propagation. The weak bonding in the NI layers gives rise to significantly low sound velocity, and the localized low-frequency vibrations of the NI layers cause strong acoustic–optical interactions and lattice anharmonicity. All these features are favorable for the realization of exceptionally low lattice thermal conductivity, and therefore present remarkable opportunities for developing high-performance thermoelectrics in weak TIs.